In the typical fuel vapor vent valve for a motor vehicle fuel tank that is adapted to prevent spillage in case of shaking, tilting or rollover of the vehicle, the valve normally opens the fuel tank to an orifice that is connected by a vapor exit passage in the valve body to a vapor hose leading to a fuel vapor storage device. The valve body is commonly made as a one-piece plastic injected molded part that has a simple direct connection between the orifice and the vapor exit passage. However, this connection has a tendency to collect and pass any liquid fuel issuing from the orifice under pressure from the tank on to the vapor storage canister. The latter contains a fuel vapor absorber such as carbon and any liquid fuel delivered thereto will quickly reduce its vapor absorbing ability. An example of such vent valve is disclosed in U.S. Pat. No. 5,044,389 granted to David R. Gimby Sep. 3, 1991 for a high volume fuel vapor release valve and assigned to the assignee of the present invention.
It is difficult to configure the top of the molded body with a vapor exit passage connection that would somehow trap this liquid fuel after it passes through the orifice and then drain the trapped liquid fuel back to the tank. This is also the case where the valve is omitted and only venting is provided through an orifice in a vent body that mounts on the fuel tank.
As to any such possible liquid fuel drainage back to the tank in the case of a vent assembly having a valve that blocks the orifice on overfill, vehicle shaking, tilting and/or rollover, adversely affecting the operation of the valve for normal venting operation in an upright position and closure under these various circumstances must be considered. Any drainage path for liquid fuel trapped downstream of the orifice can not provide a path for fuel vapor to vent around the closed valve in the normal upright attitude of the tank or allow liquid fuel to escape from the tank when tipped or inverted.
One solution to such problem is set forth in U.S. Pat. No. 5,413,137 granted to David R. Gimby May 9, 1995 for a fuel vapor vent assembly with liquid trap; also assigned to the assignee of the present invention. The fuel vapor vent assembly set forth in the '137 patent embodies a fuel impervious insert that is adapted to be mounted in such a vent valve body and defines both a vertically oriented vent orifice and a liquid basin extending about the exit of this orifice. A simple cavity formed in the interior of the top of the plastic body cooperates with the basin in the insert to define an expansive chamber elevated above the orifice with a horizontal vapor exit passage in the plastic body adapted to be connected to a vapor storage device. The expansive chamber forms an elevated liquid trap at the exit of the orifice that traps liquid from the venting fuel vapor while permitting venting to continue therethrough and then drains the trapped liquid in the basin back into the tank through the orifice in the insert when the pressure in the fuel tank is relieved. The liquid trapping chamber has a ceiling directly opposite the orifice dead ending the vapor stream issuing therefrom and the vapor exit passage is connected to the expansive chamber at a point above the basin. These features combine to aid in separating any liquid fuel out from the vapor and down into the basin and prevent it from passing on to the vapor exit passage and thence to the vapor storage canister.
While suitable for their intended purpose, the fuel vapor vent assemblies set forth in the aforesaid prior art Gimby patents do not include provision for venting vapor from the tank as the float is closing at the same rate at which the fuel tank is being filled nor do they provide a predetermined vapor dome space within said tank to accommodate vapor pressure increases when the refueling valve is closed. Further, the unitary body arrangements are configured to locate the valve seat close to the tank top and the fuel vapor openings well below the valve seat so that venting is restricted as the float moves between its normally open position and its normally closed position. Moreover, the valve disclosed in the Gimby '389 patent has a direct path for liquid fuel to splash through the fuel vapor openings of the valve body into the vapor outlet past the valve seat.
It is therefore an object of the present invention to provide a fuel vapor vent device that vents vapor during fuel fill at the same rate as the rate of fuel flow into the tank while preventing liquid fuel flow to a fuel vapor storage canister.
A further object is to provide such a device that includes a vapor exit port providing vapor venting as a rollover float component moves toward closure as fuel flows through a filler neck of a fuel tank.
Another object is to provide a fuel vapor vent device for a motor vehicle fuel tank having a vapor exit passage with a flow area large enough to vent vapors at the same rate as the fuel tank is being filled so as to prevent pressure build up in the fuel tank during fuel fill.
Another object is to provide such an arrangement wherein the body of the fuel vapor vent device includes vapor exit ports within the tank that remain open as the fuel tank is filled and wherein the exit ports are large enough to vent vapors at the same rate at which the fuel tank is being filled and wherein the vapor exit ports are provided in the body at a point high enough with respect to the valve seat of a rollover valve to prevent liquid fuel carry over to a fuel vapor storage canister.
Yet another object is to provide a fuel vapor vent device that includes a vent tube defining a valve seat and a direct connection to a vapor exit passage in the top of the cover that is connected to a tube for connecting the fuel vapor vent device to the inlet of a charcoal canister wherein the area of the vent tube and the area of the vapor exit passage are substantially equal.
Still another object is to provide a fuel vapor vent device as set forth in the preceding objects including a refueling valve having a body with a vapor exit passage and a liquid inlet passage and the body being connected to the top of a fuel tank in depending relationship therewith; the valve including a float and a valving element carried by the float and tiltable with respect to the float for compensating for tilt and further characterized by the body further including a vapor exit port adjacent the top of the fuel tank and also including a vent tube with a valve seat located a substantial distance below the tank top and located at or below the level of the vapor exit port for preventing liquid fuel particles from entering the vapor exit passage.
Still another object is to provide a fuel vapor vent device including a refueling valve having a body with a vapor exit passage and a liquid inlet passage and the body being connected to the top of a fuel tank in depending relationship therewith; said valve including a float and a valving element carried by the float and tiltable with respect to the float for compensating for tilt and wherein said body further includes a vapor exit port located above said liquid inlet; a first vent tube supported within said body having one end sealingly connected to the vapor exit passage and having an opposite end defining a valve seat closable by the valving element and located at or below the vapor exit port for separating liquid fuel particles prior to entering said vapor exit passage and further characterized by a cover member connected to the upper wall of the fuel tank outboard thereof; the cover member forming the vapor exit passage and the body including a valve housing located inboard of said fuel tank and the vapor exit ports being formed in said valve housing adjacent the upper wall of the fuel tank.
Yet another object of the present invention is to provide a fuel vapor vent device of the preceding objects further characterized by said valving element having an annular skirt and a ball joint socket thereon located concentrically of said annular skirt; said float having a ball on one end thereof connected to the ball joint socket for providing freedom of movement between the float and the valving element for adjusting the position of said valving element with respect to said annular valve seat to compensate for tilt.
Another object of the present invention is to provide a fuel vapor vent device of the preceding objects wherein the refueling valve is further characterized by said float comprising a hollow cylindrical member with a closed end and an open end and a weighted closure disc on said open end for sealing the float; said weighted closure disc having a weight selected with respect to the displacement of said hollow cylindrical member for aligning said float vertically within said body for reducing friction between the hollow cylindrical member and said housing.
These and other objects, advantages and features of the present invention will become more apparent from the following description and accompanying drawings wherein: